Insulin for gestational diabetes – what it is and how it works

Where blood sugar levels cannot be lowered and stabilised enough through dietary and lifestyle changes, or through using medication such as Metformin, some ladies will be required to use insulin for gestational diabetes.

Insulin is a hormone in the body produced by the pancreas. Your body uses insulin to move the sugar (glucose) obtained from food and drink from the bloodstream into cells throughout the body. The cells are then able to use the sugar for energy.

Bedtime insulin for gestational diabetes

Table of Contents

Bedtime insulin for gestational diabetesHere are the most commonly asked Q&A on insulin for gestational diabetes from our Facebook support group

Why do I need to take insulin for gestational diabetes?

If lower blood sugar levels cannot be reached through diet, exercise and medication such as Metformin, then many will be required insulin for gestational diabetes.  If blood sugar levels remain high, then the diabetes is not controlled and can cause major complications with the pregnancy and baby.Bedtime insulin for gestational diabetes

If your levels are rising out of target range, your own insulin production may need to be topped up at the meal time.  You may need to take insulin at one or all of your meals.  Sometimes the insulin you produce in-between your meals and overnight may also require a top up. This may mean that you require an extra slower-release insulin at bedtime and/or in the morning.

Some consultants will prescribe insulin on diagnosis of gestational diabetes on the basis of your GTT results or following other complications relating to gestational diabetes.  For the majority, you will be given some time to try diet and exercise changes and then medication such as Metformin before insulin is introduced as a way to help lower and control your levels.

NICE guidelines for timing and use of insulin for gestational diabetes

Does injecting insulin hurt? I’m scared of needles…

Needing to inject may sound daunting but the injection is simple and is actually less painful than the finger pricks you are already doing many times a day!

Insulin is administered with a very small, ultra-fine needle (needle sizes available are 4mm, 5mm, 6mm and 8mm – 5 and 6mm needles are most commonly used) into fatty tissue and the insulin comes in a pre-loaded pen style device or cartridge to fit into the pen. In the UK & ROI you will not need to use a needle & syringe and bottle of insulin.

If you have fears over injecting then discuss these with your health care professionals and use our Facebook support group for help, support and encouragement. We have all been there and felt scared and anxious too. The first injection is always the worst, but we will help you through it.

Bedtime insulin for gestational diabetes
pen style insulin device known as a ‘flexpen’
What will happen once I start taking insulin for gestational diabetes?

Balancing the insulin with the food you eat and your activity levels will keep your blood glucose levels in the normal range. This means your baby will receive the right amount of energy and food to encourage normal growth. THE DOSE OF INSULIN WILL INCREASE AS YOUR PREGNANCY PROGRESSES – this is because the further into pregnancy you go, the more insulin resistant you become due to the growing baby and the placenta working harder.  Insulin treatment also causes additional insulin resistance i.e. the more you take, the more you need. Some ladies end up on 100’s of units a day.

Bedtime insulin for gestational diabetesHow do I know how much insulin to take?

You will be advised when and how much insulin you will need to take by your diabetes health care professional. Many ladies will be given guidance on adjusting insulin doses if necessary but please do not increase or decrease doses without seeking guidance of your diabetes health care professional first.  The dose is changed by turning the dial on the end of the insulin flex pen.

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Does insulin cause any side effects?

As with any medications there are possible side effects, but the majority of ladies have no side effects from taking insulin for gestational diabetes. Some may see an allergic skin reaction at the injection site such as itching, redness, swelling etc. In rare cases insulin can cause some other side effects too.  Injecting into the same area can cause lumps under the skin and so it is advisable to move the injection site each time you inject.

If you feel you are suffering any side effects from taking insulin then speak to a medical professional straight away.

Common side effects: Insulin lowers blood sugar levels and can cause hypoglycaemia (hypos), it also increases appetite.

Will taking insulin for gestational diabetes change my birth plans?

Depending on your blood glucose levels, baby’s growth, hospital and NHS Trust guidelines, you may be advised to have an induction (or planned caesarean section if you need this for other reasons) from anywhere around 37 weeks to 40+6 weeks.

We see many ladies in our Facebook support group, advised to be induced once starting insulin for gestational diabetes and therefore many try their best to avoid insulin therapy for this reason. Unfortunately if you cannot lower and stabilise your blood sugar levels through other means, then insulin is the only solution and should not be avoided in attempt to get the birth you want, as the complications of uncontrolled gestational diabetes carries high risks.

When it comes to making birth plans, these can be discussed for you to make an informed choice around what would be best for both your baby and you. With the help of a good professional team and by researching your case, you may still be able to go on to have exactly the birth you originally planned for.

Taking insulin for gestational diabetes means that your insulin resistance is worse than that of a mother who is diet controlled or taking Metformin and therefore you may be advised different birth plans to what you had originally planned for, but even if you are advised against plans you wanted, there may be ways to find a birth plan that you are very happy with, so please do not give up hope or feel defeated. To help you with making informed choices around birth plans, please take a look at these pages for further information on timing and modes of birth on our induction and water or home births pages.

During the labour, you may be given insulin via an intravenous drip. A ‘sliding scale‘ is an IV drip with glucose and insulin (2 drips). It helps to stabilise blood glucose levels by adding glucose if you’re levels drop too low and adding insulin if your levels raise too high. Some hospitals will use them as per their Trust or hospital policy dor all with diabetes; diet, metformin or insulin control makes no difference. Other hospitals will only use them for insulin controlled mothers and some will only use them if they see blood sugar levels drop or spike to a certain level. If you have stable well controlled blood sugar levels throughout pregnancy and labour, then a sliding scale is not necessary. You should discuss with your diabetes team and consultant if a sliding scale would be used in your labour, or under what circumstances would they advise it’s use.

Bedtime insulin for gestational diabetes
sliding scale insulin and glucose drip
Is insulin available which is not in form of an injection?

Bedtime insulin for gestational diabetesThere are new insulins on the market which can be inhaled rather than injected.  These are very new, have not been tested for use in pregnancy and are not available for prescription.

There are however some oral medications available which can help lower blood glucose levels.  The most commonly used medication is called Metformin.  Another medication called Glibenclamide may also be offered as an alternative. Metformin and Glibenclamide are not able to control blood glucose levels to the extent that insulin can, therefore there is the possibility that you could be prescribed these medications but still end up needing insulin further into the pregnancy. Metformin is not an option for everyone, there are also some pregnancy conditions and medical reasons why insulin would be better suited for use.

Will I need to continue taking insulin after my baby is born?

Unless you were taking insulin previous to pregnancy, then all treatment will cease once your baby is born.

How to store insulin:

Store unopened, spare insulin in a refrigerator (it must not freeze).  The current pen you are using can be kept at room temperature but avoid direct sunlight and heat sources such as radiators, fires and window sills.  Avoid injecting it straight from the fridge as it will nip (sting)! Keep insulin out of reach of children. Avoid keeping your insulin pen with a needle attached. This will prevent others (especially children) injecting insulin or having accidents.


Where to inject insulin:

Different areas of body release the insulin at different rates. The quickest area to be absorbed from is the belly, followed by the upper arm, then the thighs and lastly the buttocks, but all these areas are suitable for injecting in to. Many find the belly the best place to inject and find that the thighs can ‘nip’ more. Vary the places you inject into to avoid the development of fatty lumps.

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Bedtime insulin for gestational diabetes
injection into the thigh
When to inject:

Please check with your diabetes consultant or midwife to see when they advise you should inject.  This will differ depending on the type of insulin and also there are differences in advice from one diabetic clinic to another.

How to inject:
  1. Bedtime insulin for gestational diabetesPrepare your insulin –  Some insulins need to be primed or mixed before use.  To do this roll the pen/cartridge between your hands ten times, keeping it horizontal, then move it from up and down, from one end to the other at least ten times. Please note:  some insulins are clear, others are cloudy.  If it’s a cloudy insulin, repeat the rolling and moving until the liquid is uniformly white and cloudy.

  2. Remove the protective tab from the disposable needle and screw the needle tightly onto the end of the pen.  Pull off the plastic outer cap and keep it as you will need it to safely remove the needle later.  Carefully remove the inner needle cap.

  3. Dial two units of insulin on the pen.  Hold the pen with the needle pointing upwards and tap the cartridge gently with your finger a few times to make any air bubbles collect at the top.

  4. Bedtime insulin for gestational diabetesPress the button all the way in.  A squirt of insulin should be dispersed.  If it doesn’t then change the needle and repeat the steps to this point again.

  5. Bedtime insulin for gestational diabetesDial the dose you need to inject.  (Please note: you cannot select a higher dose than the amount of insulin left in the cartridge).

  6. Bedtime insulin for gestational diabetesInsert the needle using the injection technique recommended by you health care professional. You may want to pinch the skin before inserting the needle.

  7. Bedtime insulin for gestational diabetesInject the full dose by pushing the button down fully.  The needle should stay in the skin for at least 10 seconds to ensure the full dose has been injected and then remove.

  8. Bedtime insulin for gestational diabetesDisposal – Lead the needle into the bigger outer needle cap without touching the actual cap to avoid accidents.  When the needle is covered, carefully push the it completely on and unscrew the needle. Dispose of the needle into a yellow sharps bin and put the lid back on the insulin pen.

visual guide to injecting

 Hypoglycaemia (Hypos)

Hypos are the main side effect of using insulin for gestational diabetes.  This can happen if your blood sugar levels drop below 4.0mmol/L (although some professionals will advise that hypo levels are below 3.5mmol/L)  A handy phrase to remember once you start insulin is “four is the floor”

Bedtime insulin for gestational diabetes

Symptoms of a hypo:
  • Sweating
  • Anxiety or bad temper
  • Trembling/shaking
  • Tingling of the lips or fingers
  • Intense hunger
  • Going pale
  • Dizziness
  • Palpitations (heart beating rapidly)
  • Confusion
  • Lack of concentration
  • Lack of co-ordination
What can cause a hypo?

Hypos can be caused by one or more of the following:

  • Missed or delayed meal or snack
  • Eating less food than usual, especially carbohydrates
  • Taking too much insulin
  • Unplanned or sustained exercise*
  • Poor site rotation for injections leading to ‘lumpy’ areas
  • Drinking alcohol without food*
  • Extremes of temperature
  • Interaction with other medications
  • Stress

Note: *Hypos may occur many hours after drinking or exercising

Once insulin treatment is started it is very important to always carry a hypo treatment kit to hand.  This only needs to be an item to treat and raise your blood sugar levels with and a slow release carbohydrate.  You also need your blood glucose test monitor.
What to use to treat mild hypos

A fast acting glucose (something high in sugar), here are some examples:-

  • 4 x glucose tablets
  • 75ml of lucozade
  • small carton of orange juice
  • small mixer size can of Coke
  • treat size bag of haribo/jelly sweets
Please note:  Chocolate is no longer recommended for using as a fast acting glucose treatment for hypos due to the fat in chocolate slowing down the release of glucose into the bloodstream
Bedtime insulin for gestational diabetes
Some clinics will give out a hypokit like this – it is only to be used for severe hypos where you have passed out. Please note: severe hypos are rare in those with gestational diabetes
  A slow release carbohydrate, here are some examples:-
  • 2 digestives/hobnobs
  • small pack of Nairns oatcakes
  • A glass of milk
  • A sandwich
  • A piece of wholemeal/granary/Burgen soya & linseed toast
  • Your next meal if you are due to eat
How to treat a hypo

Bedtime insulin for gestational diabetesStep 1.  Check your blood sugar levels – Symptoms of hypos are very similar to those of hypers (high blood sugar levels) and so it is important to ALWAYS check your levels first.  If they are 4.0 mmol/L or below then continue with the steps below.  If your levels are above 4.0mmol/L then you may be experiencing what is known as a ‘false hypo‘.

Step 2.  Eat/drink a fast acting glucose to raise the blood sugar levels rapidly and WAIT 15 mins

Step 3.  Test your blood sugar levels again –  If they are above 5.0 mmol/L then continue to Step 4.  If they are still below 5.0 then repeat Steps 2 & 3 until they are above 5.0mmol/L

Step 4.  Eat a slow release carbohydrate.  It is important to do this to stabilise your blood sugar levels and to stop them from dropping rapidly again.  This is the step that many ladies miss and then struggle with levels dropping again and having repeat hypos.

Bedtime insulin for gestational diabetes

Nocturnal hypoglycemia – Night time hypos

Nocturnal hypoglycemia (night time hypos) can be worrying as you may only spot the symptoms once you are awake. Night time hypos are common in people who treat their diabetes with insulin rather than Glibenclamide.

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Symptoms of night time hypos

Sometimes you may wake whilst having a night time hypo. If you wake and have any of the usual hypo type symptoms, then test your blood sugar levels and treat the hypo as you would during the daytime.

However, if you don’t, you may notice one or more of the following signs on waking:

  • Waking with a headache
  • Experiencing seemingly unprovoked sleep disturbance
  • Feeling unusually tired
  • Waking with damp bed clothes and sheets from sweating
  • Having a clammy neck

To prevent night time hypos try to always have a snack before bed.

Bedtime insulin for gestational diabetesSevere hypos

If you do not treat it, hypoglycaemia will become much worse and you may become semi-conscious or fully unconscious and will need to be treated by someone else.  It is advisable to explain how to treat hypos to those that you live with, including children who are old enough to understand and assist.  Severe hypos are rare for mothers with gestational diabetes.

Make sure your family and friends are aware that they must not give you anything by mouth if you are unconscious or unable to swallow.  They should call 999 in this instance. Always tell your diabetes healthcare team if you have a severe hypo


Driving whilst on insulin treatment

Remember this simple phrase for when driving, you must be “5 to drive

It is important to test your blood sugar levels before driving as it is advised that your levels are above 5.0 mmol/L to be safe to drive.

1.  DVLA

This is what the DVLA website says regarding temporary insulin treatment:-

2.  Car Insurance

You must by law, inform your insurance company if you have diabetes, no matter how it is treated.  If you fail to do so, your insurance will be invalid. Many companies may advise that it is fine and makes no difference, but to ensure you are still fully protected in the event of a claim, then we suggest that you ask the Insurer to add a note onto their system.

For more on driving and gestational diabetes, take a look at this post

I’ve started taking insulin yet my levels have not come down or seem worse?!

Everyone is started on a very small dose to start with and whilst this may make immediate difference for some, for many others it takes a while to get the dose correct.  This also proves difficult as gestational diabetes is a progressive condition, meaning it worsens as the pregnancy goes on. Taking insulin for gestational diabetes will not increase blood sugar levels. Keep in touch with your diabetes team to discuss blood sugar levels and doses as you may need to increase the dose by 2 units every few days until you see an impact. Some ladies end up on 100’s of units a day, so do not be concerned over the doses being taken to help control your blood sugar levels. In cases of extreme insulin resistance, we have seen ladies going up to around 600 units a day! Please note: doses should only be changed with the consent and guidance of your medical professionals.

Can I eat a ‘normal’ diet again?

Insulin will help you to tolerate foods better, but you should still follow a GD diet as things that raised your levels before will still have this effect (just not to such a high amount).

Could I take extra insulin so that I could eat what I fancied and still keep my levels low?

This is not advisable.  Doing this is dangerous as you are putting yourself at risk of having a hypo.  Also, the more insulin you take, the more insulin resistant you become and so inevitably will need more insulin in order to control your blood sugar levels.

We also find that as gestational diabetes is driven by hormones from the placenta, due to hormonal fluctuations, it is very difficult to judge how much insulin is required to balance out the carbohydrates you are eating (unlike a Type 1 diabetic would). By altering doses yourself, you are leaving yourself open to experiencing hypos and hypers and rollercoaster blood sugar levels which is not good for your baby trying to regulate their own insulin production.

Am I at increased risk of placenta deterioration by using insulin for gestational diabetes?
Does insulin cross the placenta and is it safe for my baby?

Insulin has been used for many years in pregnant women.  There are many different types and much research has been conducted around using insulin for gestational diabetes.  In general, we are told that “insulin does not cross the placenta” and therefore does not come in to contact with your baby. This is not strictly true as trace (tiny) amounts can cross the placenta but only if it is bound to certain antibodies.

Research links

Glibenclamide, metformin, and insulin for the treatment of gestational diabetes: a systematic review and meta-analysis

Treatment With Insulin and Its Analogs in Pregnancies Complicated by Diabetes 

Transfer of insulin lispro (Humalog) across the human placenta: in vitro perfusion studies.

Insulin glargine (Lantus) safety in pregnancy: a transplacental transfer study.

Insulin glargine (Lantus) use during pregnancy.

Benefits and Risks of Oral Diabetes Agents Compared With Insulin in Women With Gestational Diabetes: A Systematic Review


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